No, the Rhesus (Rh) factor of a person's blood cannot change on its own after birth without any treatment. The Rh factor is determined by the presence or absence of specific proteins on the surface of red blood cells. These proteins are genetically determined, and once a person is born with a particular Rh factor (positive or negative), it remains constant throughout their life.
A person's Rh factor is inherited from their parents; it is determined by the combination of genes they receive from their mother and father. For example, if both parents have a positive Rh factor, their child will also have a positive Rh factor. If one or both parents have a negative Rh factor, their child can either have a positive or negative Rh factor, depending on the specific genetic inheritance.
In certain situations, such as during pregnancy or after a blood transfusion, a person's Rh status might appear to change due to the introduction of Rh-positive blood into an Rh-negative individual. However, this change is only temporary and is due to the presence of the donated blood. Once the foreign blood is cleared from the individual's system, their original Rh factor remains unchanged.
It's important to note that the Rh factor can play a significant role during pregnancy, particularly in cases where an Rh-negative mother is carrying an Rh-positive baby. In such situations, certain medical interventions, such as Rh immunoglobulin shots, are necessary to prevent complications that may arise from Rh incompatibility between the mother and the fetus.